One of the most expensive single items that is commonly replaced in copiers and printers is a fusing roller. It is a costly item which wears out rapidly and is generally replaced by a serviceman who must connect the roller to a suitable drive, locate temperature sensors and a fusing oil applicator in contact with it without damaging its surface. Any irregularities from handling that appear in the surface of the fusing roller are likely to show up as image artifacts in the fixed image.
Japanese Patent Application 63-107319 (1988), laid-open Nov. 7, 1989 (1-277271), shows a fuser in which a large portion of the entire fuser is replaceable in a single unit. This has the advantage of protecting the parts in the fuser when the unit is outside of the apparatus, but the disadvantage of replacing the more durable pressure roller assembly with the fusing roller.
A serviceman will often replace a fusing roller as part of a service call in which he operates the apparatus to check its performance. Replacement of the fusing roller requires that he wait until the roller cools down, wasting valuable service time.